The present disclosure relates generally to equipment utilized and operations performed in conjunction with a subterranean well and, in an embodiment described herein, more particularly provides a multi-position hydraulic actuator.
Many actuators for operating downhole well tools include a piston which is displaced back and forth between two positions in response to differential pressure applied to the piston in alternating directions. For example, a valve can be opened by displacing the piston in one direction, and the valve can be closed by displacing the piston in an opposite direction.
Unfortunately, using this type of actuator generally requires that each well tool be operated using an individual actuator, and that each actuator be supplied with pressure from pressure sources via multiple lines. This increases the complexity and expense, and reduces the reliability, of systems which require operation of multiple well tools. Furthermore, design limitations of available space (design envelope) are easily exceeded when using traditional methods of one hydraulic control line for each actuator position.
Even if only a single well tool is to be operated using such an actuator, an operator is typically limited to only two configurations of the well tool corresponding to the two positions of the piston in the actuator.
Therefore, it will be appreciated that advancements are needed in the art of providing multi-position actuators for operation of downhole well tools.